http://reamo.com/

This is in their FAQ:

"Our revenue comes from the phone calls generated by you via your phone company, and all you need to do is listen to the radio stations which we stream in order to earn units. Please note that we are only able to pay out on funds which we’ve successfully received from your phone company."

How would this work? AFAIK it's not a premium number service, and it's highly unlikely that they would have contracts in place with all major telcos.